Many variations of underwater communication devices are known as used from time to time by divers in both shallow and deep diving conditions. The only reliable devices previously developed have been those of electro-mechanical or electronic construction, especially wireless communication apparatus of a portable type which requires batteries, microphones, ear phones, transistors, and the like to be maintained in watertight housings and with essential watertight connections. Such devices are extremely expensive and the cost is doubled by the fact that each diver must be fully equipped to communicate with one another.
Attempts have been made to provide non-electronic devices for talking under water, but no such devices are currently available in the marketplace. One example of a purely mechanical device is the so-called "Scuba Com" described in an article entitled "Mighty Mouth" by Jack McKenney, see the July 1969 issue of Skin Diver Magozine) as utilizing a specially compounded silicone-rubber diaphragm designed to provide a mechanical, air to water impedance matching device. However, this device just as all other known purely mechanical devices has the disadvantage that air bubbles are exhausted therefrom during its use and these air bubbles create loud cracking or popping sounds drowning out or severely masking vocal communications emitted from the acoustic diaphragm.
In addition, such mechanical devices are limited by the need to be attached to a separate air supply in order to permit the speaker to fill his lungs after each use of one breath for speaking. When so attached to separate air supply, the device becomes bulky and cumbersome and must be worn at all times as a normal air supply. If not so attached, the speaker must regain a fresh supply of air from the usual air regulator after each short spoken message.
An earlier underwater speaking device with an acoustic diaphragm formed by a thin plastic or brass disc is disclosed in U.S. Pat. No. 2,844,212 with the diaphragm being disposed directly in the air regulator, i.e. the air breathing apparatus which also includes air intake and exhaust hoses and an air tank. Some of the difficulties in using this earlier device are discussed by Laughlin et al in their subsequent U.S. Pat. No. 3,174,129, wherein these and other problems were again avoided by returning to an electromechanical combination with a microphone equipped face mask directly connected to the air regulator or breathing apparatus.